It is well known that it is common practice to use a credit card or a similar thin, flexible instrument to disengage a door latch in a door for the purpose of illegal entry therethrough. The instrument is placed between the door and the jamb at the position of the latch mechanism and is used to force the latch bolt back into the door (out of the striker plate) to allow opening of the door.
Guard plates for the prevention of such illegal entry are commonly sold. Many institutions fabricate such plates for use in their facilities. These prior art security plates are believed to be designed and fabricated to fit a particular door/latch set combination, depending upon whether the door opens inward (toward the area to be secured) or outward (away from the area to be secured). U.S. Pat. Nos. 3,888,530, issued to Fabrici; U.S. Pat. No. 3,764,173 issued to Griffith; U.S. Pat. No. 2,144,075, issued to Mora; U.S. Pat. No. 4,183,568, issued to Ferracane; U.S. Pat. No. 3,761,119, issued to Bennett et al.; and U.S. Pat. No. 3,405,962, issued to Sushan, are illustrative of the state of the art.
These prior art designs are intended for use on only one side of a door and are not adaptable to either outward or inward opening doors.
Attention is also brought to my previous application for patent on a Double Purpose Security Plate, filed on Mar. 2, 1984 and bearing application Ser. No. 585,924, now U.S. Pat. No. 4,583,776, issued Apr. 22, 1986.